A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a more resistant layer or layers of harder rock, e.g. shales overlain by sandstones. The resistant layer acts as a caprock that forms the flat summit of a mesa. The caprock can consist of either sedimentary rocks such as sandstone and limestone; dissected lava flows; or a deeply eroded duricrust. Unlike plateau, whose usage does not imply horizontal layers of bedrock, e.g. Tibetan Plateau, the term mesa applies exclusively to the landforms built of flat-lying strata. Instead, flat-topped plateaus are specifically known as tablelands.
Luyi County, Henan Province directly administered County, Zhoukou City escrow. Luyi, known as Minglu, Zhenyuan, Kuxian, Guyang and Xianyuan, is located in the east of Henan Province and the junction of Henan and Anhui provinces. It is bordered by Zhecheng County and Suiyang District of Shangqiu City to the north, Huaiyang County to the west, Dancheng County to the south, and Qiaocheng District, Bozhou City, Anhui Province to the east. Luyi is the hub connecting the Central Plains Economic Zone, the Wanjiang Economic Belt and the Yangtze River Delta. Luyi County has a total area of 1238 square kilometers and a total population of 1.18 million. Luyi is the hometown of Laozi, the founder of Taoism. In November 2011, it was examined and demonstrated by experts organized by the Chinese Folk artists Association and submitted to the China Federation of Literature and Art for examination and approval.